Roman Concrete Vaulting in the Great Hall of Trajan’s Markets: Structural Evaluation

An in-depth structural analysis is used to explore the design and functionality of the Great Hall of Trajan’s Markets (110 CE), a large Imperial monument cross vaulted in unreinforced Roman concrete. Following a combined approach, the analysis utilizes both field quantities and aggregate equilibrium quantities to determine how the load paths of the structure are utilized to support its own weight. The lateral arch is found not to provide any appreciable buttressing to the vault. Instead, the lower shear wall counters the vault thrusts after they traverse a frictional interface between the two travertine blocks of the support pier. Several facets of the design are altered in hypothetical models to reduce mechanical stresses. An improved configuration mimics later Imperial structures by lowering the lateral arch to the springing level, the horizontal displacement of which is found to directly determine tensile stress magnitudes in the vault. Comparisons with later, larger-span Imperial monuments vaulted in concrete reveal the Great Hall as a significant milestone in the evolution of Roman structural design.